I didn't intend to question that this is a common feature of
Indo-European languages. It may even be a feature of Semitic languages.

I am only saying that natural language is untidy. If all the
morphological forms had multiple simultaneous syntactical functions and
all the semantic tokens had multiple simultaneous sense and/or reference
then the difficulty of determining the sense of any given clause or
paragraph would increase geometrically.

If one was going to sit down and design a language there are certain
language features one would want to avoid. Multiple simultaneous
syntactical functions for a single instance of a morphological form in a
single context, is a language feature which would cause nasty problems
if it were not well constrained by other language features. It just so
happens that in Indo-European languages this feature of participles is
well constrained by other language features so that little ambiguity
arises.

I am sure that this is just so much gobbeldy gook to many b-greek people
so I will drop it.